Not sure if a discussion on turbos has occurred but

[wanda]

I was thinking about the old diesel engine and how noisy and lack of power, e.t.c, it was.

Now turbo diesels (and petrols) are almost automatically the norm. I was thinking what would be the best way to get rid of the initial delay before the turbo boost kicks in. Twin turbo is a good idea, i.e a mix of small and large turbos. Small one to take you to the big one.

Now BMW 550d with 3 turbos has perplexed me a bit.

https://www.youtube.com/watch?v=cqERH9fky2Q

https://www.youtube.com/watch?v=isSjS...layer_embedded

In theory they have a small turbo to boost from idle then the small one takes over then finally the big one takes over.

Assuming we reach the point where the big turbo kicks in, the other turbos can not spin or "create" the air flow that the big one can so can we assume it would automatically switch off?

I was thinking of experimenting on a 1.5 dci engine with a twin turbo system. (When money is saved).

Kingston University took the 1.5 k9k engine and reported some power gains but thought it would be more than reported.

https://www.ricardo.com/Documents/Downloads/Software%20Flyers/Conference%20Info/EUC%202011/Presentations/Kingston_WAVE_Twin-entry_Turbocharger.pdf

 

[Dubz]

A twin entry turbo. That's new to me.

Haven't BMW or Ford started developing an electric turbo? Where the electrisity starts the turbo at low rev's where exhaust gases are weak to gain more power lower down the rev range.

 

[singlespeed]

wasn't there one of the 80's Group B rally cars with a small supper charger and a huge turbo. Best of both worlds... No lag and massive boost

with emission targets leading to smaller displacement engines being the norm, i bet multi turbo engines become more common, even on 3 and 4 cylinder engines

 

[Penn]

wasn't there one of the 80's Group B rally cars with a small supper charger and a huge turbo. Best of both worlds... No lag and massive boost

with emission targets leading to smaller displacement engines being the norm, i bet multi turbo engines become more common, even on 3 and 4 cylinder engines

VW group have been using TFSI engines for years now. Supercharger for low down torque and the turbo takes over to bring more power. They even fit them to the new cylinder on demand technology that shuts down a 4 cylinder engine to 2 cylinders under low demand.